We are currently witnessing the USDA public commentary
period on the Arctic Apple, a transgenic apple that does not exhibit browning
upon injury or cutting. The
anti-browning trait was installed by scientists at Okanagan Specialty Fruits.
A copy of the apple gene for polyphenol oxidase (PPO) was overexpressed, which
triggers a plant response to silence the over-expressed gene. The same process also suppresses the apple’s
endogenous PPO genes.
Trees have been growing for ten years and are poised for widespread adoption. But as expected, the critics have now emerged
against this non-browning apple. They say that the apples are untested in humans, that the pollen will contaminate other plants. They say that it is unnatural and will need more pesticide.
But the same criticisms were strangely silent against what
was essentially the Arctic Grape. A
major genetic alteration affected the PPO gene of the ‘Sultana’ grape, a
genetic change that was unknown, uncharacterized and uninvestigated. All the scientists knew is that they didn't brown. The resulting grape exhibited the same
anti-browning properties as the current Arctic Apple, and gained rapid favor for the production of
light-colored raisins and low-oxidation wines. Unlabeled and
untested, this genetic aberration spread quickly throughout the dried-grape
industry, as consumers and farmers realized great gains from the sweet, white
and golden raisins.
Worse, it turns out that scientists later deciphered the
molecular basis for the disorder. The normal PPO protein was unprocessed, a new
protein created! Just like the anti-GMO
folks warn us about all the time, the new protein, untested for allergenicity
and long-term feeding consequences, accumulated in the modified Franken-fruit background. This new freakish protein was the unnatural reason
that the grapes did not brown, and the raisins remained white or golden.
The Punchline. You’ve
likely eaten them. You might have even
bought them at an organic market. You
In fact, the PPO mutant occurred spontaneously in 1962 in a
grape line called “Sultana”. A mutation
in the grapevine changed a gene so that the PPO oxidase protein (the one
suppressed in Arctic Apple) could not be processed and made functional. The fruits were largely white and did not show PPO activity.
Why? The active enzyme is about 40 kilodaltons in
size, but in ‘Bruce’s Sport’, the ppo mutant,
the protein was not processed. The
modified protein was not a functional PPO. A new protein was formed and caused the lack of browning. How did this mutant atrocity ever escape
regulation? Surely Monsanto ram-rodded
this through the FDA and USDA!
Not so much.
In fact, not at all.
The PPO mutant was found in 1962. Nobody cared about why the grapes didn’t
brown, they just knew was a great trait.
In 1992 scientists finally figured out that the non-browning trait was caused
by the fact that a new protein was formed in the plant, an unprocessed form of
PPO that could not complete the browning process.
The year 1962. The
year 1992. Changes in genes, new
proteins formed. All untested,
unlabeled, and accepted as perfectly fine; happy golden raisins to go with your
Turn ahead to 2012. The
same gene is suppressed in apples with great precision. A
group of people object to the process. They worry about allergies,
cross-pollination and GMO Franken-dangers.
Why is this process completely acceptable when unknown,
unpredictable and untested back in the 1960's?
Why is the process decried when it is understood, documented
and tested now?
These two questions frame an intellectual inconsistency of the anti-GMO movement that
I cannot understand, and show that it is not the product, but the process that activists find objectionable.
Rathjen and Robinson (1992) Aberrant Processing of Polyphenol Oxidase in a
Variegated Grapevine Mutant Plant Physiol. 99(4): 1619–1625.
Dry and Robinson (1994) Molecular cloning and characterisation of grape
berry polyphenol oxidase Plant Molec. Biol. 26: